August 12, 1990

On this day in history in 1990 the largest-ever Tyrannosaurus rex skeleton was discovered.

Finding Sue

Sue Hendrickson at the excavation site where they find the T-rex bones

Fossil hunter Susan Hendrickson discovered three large bones out of a cliff in South Dakota. It wound up being bones from a Tyrannosaurus rex, which were nearly complete at 90% of the skeleton and extremely well-preserved. Her employer paid the landowner $5000 to excavate the skeleton but this wound up being the beginning of a years-long ownership battle.

Although Hendrickson's company, Black Hills Institute of Geological Research, took ownership of the skeleton after its excavation the U.S. Attorney's Office claimed the dinosaur's bones were seized from federal land and government property. It was discovered the owner of the land, who was part Native-American, had traded his land to the tribe decades earlier and thus his sale for the excavation rights was invalid.

Displaying Sue

Sue at display at the Field Museum in Chicago

The dinosaur, which had been named "Sue," eventually went up for public auction in 1997 and Chicago's Field Museum purchased it for $8.36 million. It went on display in the museum three years later. It stands 13 feet high and is 42 feet long from head to toe. Its 2,000 pound skull is so heavy it can't sit on the actual skeleton and instead has its own special exhibition space, with the skeleton holding a mold instead.

The nearly-complete Sue skeleton has helped scientists learn more about the T.rex. They have learned it was a carnivorous dinosaur with incredible sense of smell. This they could learn because the skeleton showed the dinosaur's olfactory bulbs were bigger even than its cerebrum (the thinking part of the brain). They also discovered through the skeleton the dinosaur had a wishbone, which supports scientists' theories that birds are ancestors of dinosaurs.